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Abstract:

In Wireless Local Area Network, WLAN, systems, an access point supports
access using one or more frequency bands. A WLAN device transmits a query
to a WLAN access point prior to association of the WLAN device with the
WLAN access point, requesting an indication of one or more frequency
bands used by the WLAN access point to support access. The WLAN access
point receives the query from the wireless device using one of the one or
more frequency bands and transmits to the wireless device an indication
of the one or more frequency bands in response. A relative priority of
frequency bands may be provided in order to guide the WLAN device in
choosing a preferred frequency band.

Claims:

1. A Wireless Local Area Network, WLAN, access point, supporting access
using one or more frequency bands, the WLAN access point being configured
to receive a query from a wireless device using one of the one or more
frequency bands prior to association of the wireless device with the WLAN
access point and to transmit to the wireless device an indication of the
one or more frequency bands in response to the query.

2. The WLAN access point of claim 1, further configured to transmit a
beacon on each of the one or more frequency bands used for supporting
access.

3. The WLAN access point of claim 1, further configured to transmit a
priority indication, indicative of at least one preferred frequency band
from the one or more frequency bands used for supporting access.

4. The WLAN access point of claim 3, wherein the priority indication is
further indicative of a ranking for at least some of the one or more
frequency bands, the ranking identifying the relative preferred status
for accessing the access point using the respective frequency band.

5. The WLAN access point of claim 3, further configured to determine the
priority indication on the basis of an operational characteristic of the
WLAN access point.

6. The WLAN access point of claim 5, wherein the operational
characteristic comprises a load upon the WLAN access point.

7. The WLAN access point of claim 5, wherein the operational
characteristic comprises a detected interference level in respect of the
one or more frequency bands used for supporting access.

8. The WLAN access point of claim 3, further configured to determine the
priority indication on the basis of a characteristic of the wireless
device from which the query is received.

9. The WLAN access point of claim 3, wherein the WLAN access point is
configured to transmit the priority indication in response to a second
query from the wireless device requesting a priority indication.

10. The WLAN access point of claim 1, wherein the indication of the one
or more frequency bands used for supporting access comprises a plurality
of indicators, each indicator identifying a respective one of the one or
more frequency bands used for supporting access.

11. A Wireless Local Area Network, WLAN, device, configured to transmit a
query to a WLAN access point prior to association of the WLAN device with
the WLAN access point, the query requesting an indication of one or more
frequency bands used by the WLAN access point to support access.

12. The WLAN device of claim 11, further configured to receive a beacon
from the WLAN access point using a first frequency band, the query being
transmitted using the first frequency band, subsequent to reception of
the beacon.

13. The WLAN device of claim 11, further configured to receive a priority
indication from the WLAN access point, the priority indication being
indicative of at least one preferred frequency band from the one or more
frequency bands used by the WLAN access point for supporting access.

14. The WLAN device of claim 13, further configured to select a frequency
band based on the received priority indication and to initiate access to
the WLAN access point using the selected frequency band.

15. A method of operating a Wireless Local Area Network, WLAN, access
point, supporting access using one or more frequency bands, the method
comprising: receiving a query from a wireless device using one of the one
or more frequency bands prior to association of the wireless device with
the WLAN access point; and transmitting to the wireless device an
indication of the one or more frequency bands in response to the query.

Description:

TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a Wireless Local Area Network (WLAN)
access point, a WLAN device, and methods of operating a WLAN access point
or a WLAN device.

BACKGROUND TO THE INVENTION

[0002] A Wireless Local Area Network (WLAN) typically comprises at least
one Access Point (AP) and one or more WLAN devices, configured to
communicate with and connect to the AP wirelessly. The AP then provides a
network resource, such as the Internet, to each of the connected WLAN
devices.

[0003] A commonly used form of WLAN is based on the IEEE 802.11 family of
standards. The Wi-Fi Alliance trade association specifies the
requirements for interoperability of APs and devices and certifies
products meeting those requirements. Although each AP conventionally
operates independently from other APs, networks of APs spread across a
geographical area have been established, managed by a common network
operator, to facilitate easier Internet access with high data rates.

[0004] Recent developments mean that APs and WLAN devices can support
operation using multiple frequency bands. APs that are operated as part
of a network may provide such support to allow operability with a range
of different WLAN devices, some of which may support use of only a single
frequency band or a small number of frequency bands. The AP transmits
beacons using each of the frequency bands that it supports. A WLAN device
can only receive the beacon transmitted using one frequency band at any
one time to discover the existence of the AP. However, in first
generation WLAN systems, the WLAN device may have no knowledge about
whether the AP is part of a network, what functionality the AP supports
and whether the WLAN device has subscription rights to access the AP
prior to association with the Access Point. These features would only
become apparent following connection to and authentication by the AP to
enable association.

[0005] Developments in industry standards, such as IEEE 802.11u, seek to
improve the accessibility of AP networks by WLAN devices. This is
achieved by introducing new protocols which allow WLAN devices to
communicate with an AP or a server of the AP network operator prior to
association, than is prior to connection and authentication. The Generic
Advertisement Service (GAS) allows link layer communication between a
WLAN device and a server of the AP network operator via the AP. The
Access Network Query Protocol (ANQP) is a query and response protocol
(sometimes termed a pre-association protocol). Using ANQP, a WLAN device
can determine basic information about the AP and network of APs that
would otherwise have been unavailable prior to connection and
authentication. These two protocols are intended to be used together for
querying identified APs, thereby allowing the WLAN device to select an AP
appropriately.

[0006] A challenge in the development of ANQP is ensuring that the WEAN
device is provided with useful information about an AP, whilst minimising
redundant information that wastes capacity and reduces efficiency. It is
therefore desirable that ANQP is limited only to information that the
WLAN device can use beneficially in selecting an AP appropriately.

SUMMARY OF THE INVENTION

[0007] Against this background and in a first aspect, the present
invention provides a Wireless Local Area Network (WLAN) access point,
supporting access using one or more frequency bands. The WLAN access
point is configured to receive a query from a wireless device using one
of the one or more frequency bands prior to association of the wireless
device with the WLAN access point and to transmit to the wireless device
an indication of the one or more frequency bands in response to the
query. Preferably, the query and response use the Access Network Query
Protocol (ANQP). Preferably, the Access Point supports access using a
plurality of frequency bands. A wireless device may be understood as
another term for WLAN device and is typically a client station (STA).

[0008] Existing systems require the WLAN device to scan one frequency band
at a time, so as to receive the beacon transmitted by the AP on that
frequency band prior to association of the STA with the AP. The
pre-association period is normally understood as being prior to security
authentication and assignment of a link and/or network layer identifier
(such as one or more of an Ethernet and IP address) by the AP, network or
both. During this period, it is difficult for any wireless devices to
obtain any information about the AP, other than what is broadcast in the
beacon.

[0009] For a WLAN device that also supports multiple frequency bands, it
can only query such an AP using one frequency band at a time. Moreover,
ANQP may limit the data provided only to information related to the
frequency band using which the WLAN device has made the query. This makes
it difficult for the WLAN device to make an informed selection of AP and
an informed selection of the frequency band on which to connect to that
AP, since it remains unaware of the AP functionality in respect of other
frequency bands from that using which the WLAN device made its query.

[0010] By transmitting an indication of the one or more frequency bands
using which the AP supports access, the WLAN device can identify these
frequency bands without the need to scan all frequency bands and
determine if a beacon can be received. This also minimises the number of
steps needed by the WLAN device in making a more informed decision about
the frequency band on which it should associate to the AP. Scanning of
certain frequency bands (such as 5 GHz) may be particularly power
consuming for the device, in view of the large number of channels to
scan. Power consumption is especially critical for mobile devices.
Moreover, the AP may benefit in a more balanced traffic load by provide
WLAN devices with information about the possibility of using alternative
frequency bands.

[0011] Although the term AP is used, it may be understood that an AP is
limited to a single frequency band. In such a case, the term AP as used
herein should be understood as referring to a group of access points in
the same Extended Service Set (ESS). The frequency band can also be
referred to as an Operating Class. For example, a list of Operating
Classes is defined in Annex E of IEEE Draft P802.11-REVmb-D12.0, Part 11:
Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications, November 2011.

[0012] In the preferred embodiment, the response is transmitted using the
same one of the one or more frequency bands as was used for the query.

[0013] The WLAN access point is optionally further configured to transmit
a beacon on each of the one or more frequency bands used for supporting
access. Alternatively, the WLAN access point may transmit a beacon on one
or more than one of the one or more frequency bands used for supporting
access. As a further alternative, the WLAN access point may transmit a
beacon advertising the presence of the access point as part of a network
on none of the one or more frequency bands used for supporting access.
For example, it is possible to hide the Service Set Identification (SSID)
in the beacon. The beacon is present, so that an STA can find the AP, but
excluding the SSID from the beacon may mean that the operator does not
advertise the presence of a network in a second or further band.

[0014] Advantageously, the invention may allow a multiband AP to advertise
the support of frequency bands other than the one using which a WLAN
device detected it. As a further optional enhancement, the WLAN Access
Point may be further configured to transmit an indication of specific
channels (frequency sub-bands) within advertised frequency bands, using
which the beacon of the AP is transmitted. This may mitigate the need for
the WLAN to scan all channels on the indicated frequency band and thereby
reduce power consumption further.

[0015] Preferably, the WLAN access point is further configured to transmit
a priority indication, indicative of at least one preferred frequency
band from the one or more frequency bands used for supporting access.
Advantageously, the priority indication is further indicative of a
ranking for at least some of the one or more frequency bands, the ranking
identifying the relative preferred status for accessing the access point
using the respective frequency band. Thus, the AP may respond to the
query by indicating one or more preferred frequency bands, to assist or
guide a decision of the wireless device about which frequency band to use
for access. A ranking may be used to indicate the relative priority of
the different bands. In some embodiments, the AP may be configured only
to transmit an indication of at least one preferred frequency band from
the one or more frequency bands used for supporting access. In other
words, only the preferred frequency band or bands are provided in
response to the query. The preferred frequency band or bands may be
different from the band used by the wireless device to query the AP.

[0016] In some embodiments, the priority indication is provided in
addition to the indication of the one or more frequency bands transmitted
in response to the query. Optionally, the WLAN access point may be
configured to transmit the priority indication in response to a second
query from the wireless device requesting a priority indication or an
indication of a preferred frequency band. In other words, transmitting a
priority indication may be made in response to a separate query from the
wireless device to the initial query to which the indication of the one
or more frequency bands used for supporting access was transmitted in
response.

[0017] Beneficially, the WLAN access point may be configured to determine
the priority indication on the basis of an operational characteristic of
the WLAN access point. The operational characteristic may comprise a load
upon the WLAN access point in some embodiments. Additionally or
alternatively, the operational characteristic may comprise a detected
interference level in respect of the one or more frequency bands used for
supporting access. This allows the AP to guide the wireless device
towards a frequency band which it can use to improve its access to the
AP. The wireless device may still have the possibility to decide the
frequency band that it uses for accessing the AP. Alternatively, the
wireless device may use the preferred frequency band if there is only
one, or one of the preferred frequency bands if there is more than one.
The wireless device may use the ranking to further enhance a decision.

[0018] In further embodiments, the WLAN access point may be configured to
determine the priority indication on the basis of a characteristic of the
wireless device from which the query is received. Optionally, both the
characteristic of the wireless device and the operational characteristic
of the WLAN AP may be used, although alternatively only one might be
used. Thus, the AP may additionally or alternatively use information
about the wireless device, such as subscription information or
information about the hardware, software or both of the wireless device
to provide preference information that is tailored to the wireless
device. To this end, the WLAN access point is optionally further
configured to communicate with a database. The database may be configured
to store subscription data for a plurality of wireless devices and the
characteristic of the wireless device may be determined using
subscription data for the wireless device from which the query is
received.

[0019] The indication of the one or more frequency bands used for
supporting access preferably comprises a plurality of indicators. Each of
these may be termed an Operating Class indication Element. Each indicator
may identify a respective one of the one or more frequency bands
(Operating Class) used for supporting access. The indicator may use the
values defined in Annex E of IEEE Draft P802.11-REVmb-D12.0, Part 11:
Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications, November 2011. Alternatively, the indication of the one
or more frequency bands used for supporting access may comprise a single,
indicator. The single indicator may identify a specific combination of
one or more frequency bands used for supporting access.

[0020] In a second aspect, there is provided a Wireless Local Area Network
(WLAN) device, configured to transmit a query to a WLAN access point
prior to association of the WLAN device with the WLAN access point. The
query requests an indication of one or more frequency bands used by the
WLAN access point to support access.

[0021] Optionally, the WLAN device is further configured to receive a
beacon from the WLAN access point using a first frequency band. In this
case, the query may be transmitted using the first frequency band,
subsequent to reception of the beacon.

[0022] In some embodiments, the WLAN device is further configured to
receive a priority indication from the WLAN access point. The priority
indication may be indicative of at least one preferred frequency band
from the one or more frequency bands used by the WLAN access point for
supporting access. Then, the WLAN device may be optionally further
configured to select a frequency hand based on the received priority
indication. It may then be further configured to initiate access to the
WLAN access point using the selected frequency band.

[0023] It may also be recognised that a WLAN device according to this
second aspect may have features to correspond with any of those described
in connection with the WLAN AP according to the first aspect.

[0024] In a third aspect, there is provided a method of operating a
Wireless Local Area Network (WLAN) access point, supporting access using
one or more frequency bands. The method comprises; receiving a query from
a wireless device using one of the one or more frequency bands prior to
association of the wireless device with the WLAN access point; and
transmitting to the wireless device an indication of the one or more
frequency bands in response to the query. It will be understood that this
method can optionally comprise steps or features used to carry out any of
the actions described in connection with the WLAN AP detailed above
according to the first aspect.

[0025] There may be provided in a fourth aspect, a method of operating a
Wireless Local Area Network (WLAN) device. The method comprises
transmitting a query to a WLAN access point prior to association of the
WLAN device with the WLAN access point. The query requests an indication
of one or more frequency bands used by the WLAN access point to support
access. It will be understood that this method can optionally comprise
steps or features used to carry out any of the actions described in
connection with the WLAN device detailed above according to the second
aspect.

[0026] In a yet further aspect, the present invention may be found in one
or more of a computer program (such as a connection manager) and an
operating system device driver, configured when operated by a processor
to carry out any of the methods described herein. Alternatively, the
present invention may be embodied in programmable logic, configured upon
operation to carry out any of the methods described herein.

[0027] Any combination of the individual apparatus features or method
features described may also be implemented, even though not explicitly
disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The invention may be put into practice in various ways, one which
will now be described by way of example only and with reference to the
accompanying drawing in which:

[0029] FIG. 1 shows a communications flow between a WLAN AP and a WLAN
device in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0030] The invention relates to a Multi-band Access Point (AP). Existing
access points have used 2.4 GHz, but frequency bands in the area of 5 GHz
have become available. Further frequency bands may become available in
due course, such as 60 Ghz and television "whitespace". The 5 GHz band
has both advantages and drawbacks compared to 2.4 GHz, for example
coverage and Dynamic Frequency Selection (DFS) support. However, the
migration from 2.4 GHz to 5 GHz presents some benefits for users
(increased QoS for some priority stream, load balancing). The
availability of the two or more bands with multiband devices opens up
more opportunities, assuming the fact that some multiband requirements
are fulfilled. Moreover, the existing frequency bands may also be
sub-divided into channels, each of which could be considered as a
separate frequency band.

[0031] More and more access points are available in the market and those
which are compatible with IEEE 802.11n are dual band capable, in
switchable (2.4 or 5 GHz) or concurrent Band (2.4 and 5 GHz in the same
time) mode. Devices supporting dual band are for the moment almost all
switchable capable (2.4 or 5 GHz).

[0032] A Multi-band Access Point (AP) consists of separated components,
one per band without any dialogue between them. The Service Set
Identification (SSID) broadcast by the components could be the same or
could be different, such that this may appear to the user as separated
networks, despite being provided by the same physical Access Point.
End-users do not normally understand the concept of frequency bands and,
in general, the notion of band, channel or any communication parameters
such as rates, should be hidden from the user.

[0033] Referring first to FIG. 1, there is shown a communications flow
between a WLAN AP (Multi-band AP) and a WLAN device (STA) in accordance
with an embodiment of the present invention.

[0034] The multi-band AP supports access using two different frequency
bands, band 1 (2.4 GHz) and band 2 (5 GHz). It transmits a beacon on both
bands 1 and 2. Band 1 typically provides overlay coverage. The beacon on
band 1 also indicates that the multi-band AP supports IEEE 802.11u. Both
of these beacons are received by the WLAN device STA. The STA then makes
a query on band 1 using the access network query protocol (ANQP). This
involves the transmission from the STA to the multi-band AP of a generic
advertisement service (GAS) message using ANQP. This message is a request
that uses a specific query list, in accordance with the Wi-Fi Alliance
Passpoint Certified® query list, which will be described below. This
includes a request for an indication of operating class.

[0035] The multi-band AP then responds with a GAS/ANQP message that
includes an indication of operating class. The operating class identifies
the frequency bands that the multi-band AP supports for access. In
particular, these are band 1 and band 2 in this example. The STA may then
switch to band 2 and begin the security association procedure with the AP
belonging to the same operator, without repeating the ANQP/GAS exchange.
The STA may be able to identify the AP on band 2 using its beacon,
indicating one or more of the following information in the beacon frame:
same SSID; same country information; AP is a member of the Multiple Basic
SSID (BSSID) set; same Interworking information or same Roaming
Consortium information.

[0036] As described in IEEE P802.11u-2011, Amendment 9: Interworking with
External Networks, the following shows the format of the Passpoint
Certified® ANQP Element, with the length (in octets) of each part of
the message underneath. The ANQP Element is the message transmitted
between the STA and AP.

[0037] The Info ID field is a 2-octet field whose value is for the ANQP
vendor-specific list (see Table 7-43bk in IEEE P802.11u-2011, Amendment
9: Interworking with External Networks). The Length field is a 2-octet
field whose value is set to 6 plus the length of the Payload field. The
OI is a 3-octet field and is defined in section 7.3.1.31 of IEEE
P802.11p-2010, Amendment 6: Wireless Access in Vehicular Environments.
The OI field is set to the value used by the Wi-Fi Alliance. The Type
field is a 1-octet field allocated from the Wi-Fi Alliance Technology
Identifier Assignments (TIA) number-space to indicate a Passpoint
Certified® ANQP element type. The Subtype field is a 1-octet field
whose value identifies the Passpoint Certified® ANQP element. Values
for the Subtype will be discussed below. The Reserved field is a 1-octet
field to ensure that the header of the ANQP element is word aligned. The
Payload field is a variable length field containing information specific
to the Passpoint Certified® ANQP element.

[0038] The following table shows the Subtype Value for each Passpoint
Certified® ANQP Element.

[0039] A new subtype numbered 7 is defined within the Passpoint
Certified® ANQP element.

[0040] Thus, in order to determine the frequency bands supported by the
AP, the STA makes a GAS/ANQP request to the Multi-band AP containing the
subtype `Operating Class Indication. In response to this ANQP Query for
operating Class Indication, the Multi-band AP sends a GAS/ANQP response
which contains information about the operating class of the multiband AP.
The ANQP response has the same format as described above, with an
appropriate payload. The format of the payload is shown below, with the
length (in octets) of each part of the payload underneath.

[0041] The Operating Class Indication element provides information on the
groups of channels in the frequency band or frequency bands that the
Multi-band AP uses. In other words, this element reports the operating
classes of APs in the same ESS as the AP transmitting this element. An
STA supporting more than one frequency band (for example, 2.4 GHz and 5
GHz) may use this element for Basic Services Set (BSS) selection
purposes.

[0042] This element allows APs supporting more than one frequency band to
advertise itself only on one of its supported frequency bands. It also
circumvents the need for multi-band supported STAs to search all
frequency bands and the need to perform ANQP pre-associations per
frequency band.

[0043] The Operating Class Indication field indicates the Operating Class.
The indicator used comes from the values defined in Annex E of IEEE Draft
P802.11-REVmb-D12.0, Part 11: Wireless LAN Medium Access Control (MAC)
and Physical Layer (PHY) Specifications, November 2011. The STA can then
choose one of these operating classes for accessing the Multi-band AP and
for operation after association.

[0044] Thus, an AP can provide a list of supported bands in response to a
GAS/ANQP query from the STA. However, it is also desirable for the
signalling to indicate a preferred band. The possibility to signal a
preferred band allows the AP to steer multi-band STAs towards a specific
band. This can be useful for load balancing and operational and
maintenance purposes. Moreover, the signalling of multi-band support can
be further optimised.

[0045] In order to implement a preferred band signalling and optimise the
signalling on supported band combinations, the STA can transmit a
GAS/ANQP query for the preferred band of operation. This can be
implemented by adjusting the Subtype Value for each Passpoint
Certified® ANQP Element, as shown in the following table.

[0046] In response to the Operating band Query (Subtype 8), the AP
provides a GAS/ANQP response with an Passpoint Certified® ANQP element
containing the payload `Operating band`. The format of the Operating Band
payload is shown below, with the length (in bits) of each part of the
payload above.

TABLE-US-00005
Bits: B0-B2 B3-B7
Preferred Band Band Combination

[0047] The Preferred Band subfield indicates the frequency band for the
STA to operate after ANQP pre-association. The value of the Preferred
Band subfield is set to one of the values in the table below. In case the
AP supports MIMO across different frequency bands, it may indicate the
Preferred Band subfield as `None`.

[0049] The reserved values in Table 3 and Table 4 allow for future bands
such as 60 GHz and TV White Space to be specified.

[0050] Although an embodiment of the invention has been described above,
the skilled person will recognise that various modifications or
adjustments can be made. For example, the specific formats of the ANQP
element may change and the skilled person may further appreciate that
extensions of GAS and ANQP or protocols with similar effect to GAS and/or
ANQP might be used. It is additionally or alternatively possible for the
AP to signal a priority list or ranking of the operating bands. This can
be effected by listing the bands in order of priority when providing the
response or by providing an additional data item that can be sent with
the list of bands either automatically or as an option, or transmitted in
response to a separate request from the STA.

[0051] Also, the supported frequency bands (operating classes) and
preferred frequency bands can be indicated using different formats. For
example, the table below shows an alternative format for operating bands,
with an 8-bit length rather than a 4 bit length. The skilled person will
also conceive alternative formats, and those in which the operating
classes or operating bands are sent separately from the preferred band.

[0052] Possible applications of the invention can now be considered. For
example, it may be used in conjunction with video or high priority
services. Data traffic is initiated using 5 GHz between an AP and a
wireless station because the expected performances are better. But a new
video service delivery is required between the AP and the STA. The
quality of service of this video traffic is affected by contention.

[0053] To solve the problem, the AP should be able to switch data traffic
between AP and STA connected in 5 GHz to the 2.4 GHz, to free the 5 GHz
channel for video. The invention might be used to implement this.

[0054] Another example concerns load balancing between frequency bands. A
station wishes to join the AP. The 2.4 GHz or 5 GHz bands are suitable in
term of Received Signal Strength Indication (RSSI). In a first scenario,
several stations are already connected on one band (2.4 or 5 GHz). Thus,
the AP can take the decision to connect a new station on the less crowded
band or moves an existing station on to the less congested band. In a
second scenario, the AP wants to reserve one band for a dedicated service
that requires eligibility. The AP may take the decision to indicate the
appropriate band to recommend the STA to connect.

[0055] These desideratum can be achieved in either scenario using the
following procedure. Where the STA has not associated with the AP and the
STA and AP both support the Passpoint Certified® INQP GAS protocol,
the AP can indicate the preferred band for the STA to connect in the ANQP
message. The AP Controller will have visibility of the load on the AP per
frequency band and can use this information to determine the least loaded
frequency band.

[0056] Providing an exact channel frequency may not be practical or
optimal, because the AP Controller may not know the exact location of the
STA and the APs closest to the STA. However, APs may be able to assess
the interference on channels which are part of the advertised frequency
band, in order to decide on which channel to operate for those bands. If
the AP has information on the channel on which it is operating, it can
transmit that to the wireless device to speed up access further. It
should be noted that single-band STAs can ignore the preferred band
indicated by the AP and it will not be prevented from associating with
the AP in a band different to the one preferred by the AP. Nevertheless,
it is expected that STAs supporting more than one band should follow the
AP's preferred band. This might be mandatory in some cases.

[0057] A second example relates to load balancing per service stream
between bands. Here, a station wishes to join the AP. It has a video
traffic stream and a data traffic stream. For multiple streams on various
STAs, the AT wants to reserve 5 GHz for video and 2.4 GHz for data. The
AP can then switch the video stream to use 5 GHz and the data traffic can
be streamed using 2.4 GHz.

[0058] A third example concerns interference on the 2.4 GHz band. A jammer
(for example, an alarm transmitter) is detected and there are no more
channels available. Then, the AP may switch its traffic from 2.4 GHz to 5
GHz. This scenario may not be applicable for public Wi-Fi access due to
the reliance on 2.4 GHz as the popular band used by many mobile devices.

[0059] A fourth example deals with interference in 5 GHz. Regulations that
apply to the 5 GHz band in most domains require Wi-Fi access networks
operating in this band to implement a mechanism to avoid co-channel
operation with radar systems and to ensure uniform utilization of
available channels. When radar is detected on a channel, or if there are
other services (that is non-radar) already operating on the Wi-Fi
allocated band or channel, which are not to be used by the STA, the
following steps can be taken.

[0060] Where an STA is already associated with the AP, the AP moves the
associated STA to another channel in the 5 GHz band. Were the STA is not
yet associated with the AP and both support the Passpoint Certified®
ANQP GAS protocol, the AP can indicate the preferred band and frequency
range within the band to the STA in the ANQP message.

[0061] The objectives of this band-steering include, but are not limited
to: (i) for load balancing; (ii) segregate device/usage type to specific
bands; and (iii) to ensure Passpoint Certified® access can be charged
(difficult to justify charging users if all mobile devices are charged
the same for using a Passpoint Certified® AP and a non-Passpoint
Certified® AP).

[0062] The AP can therefore use the following one or more of the following
factors to steer the STA to a desired band: (i) the current load on the
AP Controller per AP per band; (ii) the number of available channels
managed by the AP controller (taking into consideration operating
restriction, interference, etc); and (iii) traffic and/or usage type per
AP per band.

[0063] Thus, the invention may have the following advantages. It may allow
the STA to automatically switch frequency band. For a simpler user
experience, a behaviour as simple as provided using cellular systems may
be targeted. When a user is connected on a GSM or 3G network, for
example, the user will not know the frequency band being used. This is
managed by the operator. To be efficient and provide an improved user
experience, the inter band switching during communication is desirably
transparent for users, being automatic, without any user action. Also,
the security implementations that are currently frequency band-specific
may be extended across bands, using a single key. In other words, the
re-association procedure is improved.

[0064] To increase efficiency provided by multiple band, multi-band
contention and interferences management in the AP, load balancing per
user and per stream is desirable. This is assisted by switching sessions,
based on a decision from the AP. For example, high priority services
and/or video may be provided only using 5 GHz and other data using 2.4
GHz. This band reservation may be implemented by switching traffic
initiated in the wrong band, just after authentication

[0065] To implement this, the wireless device advantageously supports and
control automatic transition between or across Wi-Fi spectral bands.
Additional capabilities may be provided to enable service selection or
invocation related to band selection (for example, quality of service or
video). Also, APs may have the capability to enforce or enable band
transition and channel selection.

Patent applications by VODAFONE IP LICENSING LIMITED

Patent applications in class Contiguous regions interconnected by a local area network

Patent applications in all subclasses Contiguous regions interconnected by a local area network